A particle moving in a straight line covers half the distance with speed of 3m/s. The other half of the distance covered in two equal time intervals with speed of 4.5 m/s and 7.5 m/s respectively. The average speed of the particle during this motion is

4.0 m/s

The correct answer is Option (1) → 4.0 m/s

Average speed is given by

$v_{av}=\frac{2v_0(v_1+v_2)}{2v_0+v_1+v_2}$

$=\frac{2×3(4.5+7.5)}{(2×3)+4.5+7.5}=4 m/s$